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Making an Inexpensive Seed Warming Mat

Thursday, March 8, 2012

I start seeds indoors because I want to get a jumpstart on spring planting with strong healthy transplants. All the advice I’d read recommended buying a seed tray warming mat or a kit that included a seed tray and a warming mat (the warmer soil speeds up seed germination). But, being the frugal gal that I am, I found the mats to be somewhat pricey, not to mention their limited usefulness. Once our weather warmed up (usually by late March) I could easily use solar power to warm my newly planted seeds. In the cooler months of January, February and early March, however, I still wanted to get my seeds off to a good start, so I put my thinking cap on to come up with a solution.

Actually the idea came to me as the result of a painful situation. I had strained my back unloading bags of feed with my daughter. As I lay on the sofa with a heating pad wrapped around my back and a seed catalog in my hands it came to me! I could use the two heating pads we kept in the bathroom cabinet in place of commercial warming mats. They were a decent size, easily big enough to hold two of the black nursery flats I had gotten to hold my seed trays and recycled pony packs.

The only challenge now was to find a way to protect the heating pads from the damp seed trays so it could continue being used for its intended purpose. I looked around the house to see what I had that might work and came across an old metal tray with a ½-inch lip around the edge. It could easily hold a good number of peat pots and peat pellets and a recycled cookie sheet could hold the pony packs. Viola! Homemade seed warming mat.

Since each heating pad has different settings I had to test each setting until I found one that would warm the tray and subsequently the soil to the right temperature, which can be as low as 44 for cool weather crops like cabbage and as high as 86 for warm weather vegetables like squash and tomatoes. A good rule of thumb is 50 to 70 for most seeds. I used a standard household thermometer to measure the temperature. Now when I plant seeds indoors they get the warmth they need and I get my garden planting off to an early start.